Journal of Chemical Sciences

, Volume 120, Issue 1, pp 187–194

Understanding the folding process of synthetic polymers by small-molecule folding agents

Article

DOI: 10.1007/s12039-008-0022-3

Cite this article as:
Ramkumar, S.G. & Ramakrishnan, S. J Chem Sci (2008) 120: 187. doi:10.1007/s12039-008-0022-3

Abstract

Two acceptor containing polyimides PDI and NDI carrying pyromellitic diimide units and 1,4,5,8-naphthalene tetracarboxy diimide units, respectively, along with hexa(oxyethylene) (EO6) segments as linkers, were prepared from the corresponding dianhydrides and diamines. These polyimides were made to fold by interaction with specifically designed folding agents containing a dialkoxynaphtha-lene (DAN) donor linked to a carboxylic acid group. The alkali-metal counter-ion of the donor carboxylic acid upon complexation with the EO6 segment brings the DAN unit in the right location to induce a charge-transfer complex formation with acceptor units in the polymer backbone. This two-point interaction between the folding agent and the polymer backbone leads to a folding of the polymer chain, which was readily monitored by NMR titrations. The effect of various parameters, such as structures of the folding agent and polymer, and the solvent composition, on the folding propensities of the polymer was studied.

Keywords

PolyimidesNMR titrationfoldamerfolding agent

Copyright information

© Indian Academy of Sciences 2008

Authors and Affiliations

  1. 1.Department of Inorganic and Physical ChemistryIndian Institute of ScienceBangaloreIndia